1. Field of Invention
This invention relates to augmentation burning in a mixed flow turbofan engine and more particularly to such a construction in which vorbix burning principles are used.
2. Description of the Prior Art
In the turbojet engine art, combustion takes place in the main combustion chamber between the compressor and the turbine of the engine and may also take place downstream of the turbine in the afterburner portion of the engine. In the early combustion art in turbojet engines, combustion was sustained in the main combustion chamber by establishing a recirculation zone as in Clark U.S. Pat. No. 2,525,206, Brown U.S. Pat. No. 2,676,460, and U.S. Pat. No. 2,560,207 to Berggren. In the afterburner art it was conventional to use flameholders of the type shown in U.S. Pat. No. 2,702,452.
From these types of combustion apparatus, the art advanced to the swirl burner principles taught in my U.S. Pat. Nos. 3,788,065 and 3,701,255, and divisions thereof, and to the vorbix burning principle taught in my pending U.S. patent application Ser. No. 406,771 filed October 15, 1973.
In turbofan engines of the mixed flow design in which fan air and the engine exhaust gases flow in a common exhaust duct, the engine cycle has a high temperature rise so that it is only practical to perform augmentation combustion in the fan air stream and by utilizing apparatus which produces minimum loss. Special and unique combustion problems are encountered in such augmentation combustion and the teaching herein is to sustain augmentation combustion in such a turbofan engine utilizing the vorbix burning principles.